The object of this invention is a motor vehicle headlight device comprising essentially a combined mirror and deflection element designed to produce a light beam whose interruption is not flat. The essential object of the invention is to provide an improvement in the headlight device of prior art, this improvement consisting in the introduction of modifications to the surfaces of the mirror and/or deflection element in order to obtain an interruption of the light beam produced that is not flat. The headlight device, initially designed as a fog light, may therefore be used as a headlight device of the dipped headlight type in particular.